Line two baking sheets with parchment paper, cut to fit into the tray so that it lies completely flat. Set aside.

With a mesh sieve, sift almond flour and powdered sugar onto a piece of parchment paper, scraping any chunks through with a spatula. Discard any large pieces. Return mixture back to bowl and sift a second time. Set aside.

In a large bowl, use an electric mixer or stand mixer with whisk attachment to beat the egg whites on medium speed until it resembles cappuccino foam.

Slowly add in the granulated sugar, ⅓ at a time, while whisking on high speed.

When the meringue reaches soft peaks, use a toothpick to add in a small amount of orange gel food colouring.

Continue whisking until meringue reaches stiff peaks.

Add in half of the sifted almond flour & powdered sugar mixture into the meringue.

Gently fold in with a rubber spatula until just incorporated.

Add in the rest of the almond flour mixture and continue folding. Press the batter up around the sides of the bowl and scrape back together in a folding motion to deflate some air out of the meringue. Stop folding when you can lift up the batter and drip it off the spatula in a figure 8 motion without the batter breaking.

Transfer batter to a piping bag fitted with a round piping tip.

Holding the piping tip perpendicular to the baking sheet and close to the surface, pipe small 1-inch circles onto the prepared baking sheets by holding the piping bag in the same position and letting the batter move outwards from the tip. Leave about 1 inch space between each macaron.

Firmly lift and drop baking sheet on countertop a few times to bring any air bubbles to the surface.

Leave the baking sheets in a cool area to rest macarons for 30 mins to 1 hour.

When you can brush the top of a macaron with a finger and it doesn't feel sticky, insert one tray at a time into the oven on the middle rack. Bake for about 15-16 mins.

Remove macarons from oven when the feet have set and the macarons peel cleanly off the parchment paper.

Let cool completely before filling.

In a large mixing bowl, beat butter with an electric mixer on medium-high speed until light and creamy.

Add in powdered sugar and beat on low-medium speed until smooth.

Add the vanilla extract and orange zest and beat until smooth.

Add one teaspoon of orange juice at a time, mixing in between each addition until a smooth consistency is achieved. If buttercream is too dry, add another teaspoon of juice. If it's too wet, add more powdered sugar.

Transfer buttercream into a piping bag fitted with an open star tip.

Pair up each macaron shell with another similarly sized shell. Flip one upside down.

Pipe buttercream into the center of the bottom shell until the almost at the edges.

Gently sandwich with the other macaron shell.

Store macarons in an airtight container in the fridge for at least 24 hours to allow the shells to soften and mature. Bring macarons back to room temperature before serving.